如何为Firebase数据库异常添加内置类的无参数构造函数？

Question

我正在尝试从Android中的Firebase实时数据库中获取FirebaseLocationData对象。

根据Docs，该类不应具有我已经做过的参数构造函数， public FirebaseLocationData() {}但仍显示错误

com.google.firebase.database.DatabaseException: Class android.location.Location does not define a no-argument constructor. If you are using ProGuard, make sure these constructors are not stripped.

我怎么做一个 无参数的构造函数 的 android.location.Location 类？

该行产生错误 FirebaseLocationData fld = dataSnapshot.getValue(FirebaseLocationData.class);

码：

 public void onChildAdded(DataSnapshot dataSnapshot, String previousChildName) {
            Log.d(TAG, "onChildAdded:" + dataSnapshot.getKey());

            FirebaseLocationData fld = dataSnapshot.getValue(FirebaseLocationData.class);
            Toast.makeText(MainActivity.this, fld.getEmail()+" added", Toast.LENGTH_SHORT).show();

        }

FirebaseLocationData类：

public class FirebaseLocationData {
String email;
Location location;
String time;

public FirebaseLocationData() {
}

public FirebaseLocationData(Location location, String email, String time) {
    this.location = location;
    this.email = email;
    this.time = time;
}

public String getEmail() {
    return email;
}

public void setEmail(String email) {
    this.email = email;
}

public String getTime() {
    return time;
}

public void setTime(String time) {
    this.time = time;
}

public Location getLocation() {
    return location;
}

public void setLocation(Location location) {
    this.location = location;
}

}

Answer 1

您正在尝试编写一个android.location.Location对象， 并且
该类没有公共的，无参数的构造函数。许多Android库类无法满足Firebase的要求，因此您必须编写自己的序列化/反序列化才能与数据库交换必要的信息。